1. Field of Invention
The invention relates to the field of optical components such as solid state laser diodes and particularly to the field of light sources for fiber optic applications. The invention provides for improved alignment of pigtails or optical fiber used to couple light from an optical source out of a package for use in an application. Use of the invention in the fabrication of solid state laser diodes will reduce the cost, and increase the performance and uniformity of such products.
2. Related Art And Background
Fabrication of solid state laser diodes requires that the optical port on a laser diode chip be aligned with the polished end of an optical fiber. The laser diode product is made by metalizing an alumina substrate in predetermined areas, soldering a laser diode chip to one of the predetermined areas, soldering the substrate to a TEC or to a stack of TEC coolers. An optical fiber is prepared with metalization.
The optical fiber or pigtail is then aligned to receive the greatest amount of light from the optical port before it is soldered to the substrate. The assembly is then temperature cycled to relieve stresses on the substrate that tend to cause miss-alignment. The assembly process is concluded with a final test to see if the retained output power has remained within acceptable limits. There is a possibility that a device that had good retained power before mounting might have inadequate retained power after mounting and thermal cycling. Output power is sometimes lost as a result of warping of the substrate during the mounting process or during a reflow process.
Substrate warping and cracking is sometimes caused by the heat that must be applied to the substrate to melt the solder ball used to attach the optical fiber to the substrate. All components being mounted to the substrate or the TEC using metallurgical bonding, the substrate provides a low thermal resistance path to the laser chip and to the TEC thereby increasing the amount of heat that has to be delivered to the solder ball and the substrate to melt the solder ball. In addition to a larger amount of heat, the duration of the application of the larger amount of heat is extended because heat is drawn away from the work by the TEC.